package com.chengxuunion.util.security;

import java.io.ByteArrayOutputStream;
import java.security.Key;
import java.security.KeyFactory;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.NoSuchAlgorithmException;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.Signature;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.InvalidKeySpecException;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.util.HashMap;
import java.util.Map;

import javax.crypto.Cipher;


/**
 * RSA算法工具类
 *
 * @author kutome
 * @date 2018年8月30日
 * @version V1.0
 */
public class RSAUtils {

	/**
     * 加密算法RSA
     */
    public static final String KEY_ALGORITHM = "RSA";
    
    /**
     * 签名算法
     */
    public static final String SIGNATURE_ALGORITHM = "MD5withRSA";

    /**
     * 获取公钥的key
     */
    private static final String PUBLIC_KEY = "RSAPublicKey";
    
    /**
     * 获取私钥的key
     */
    private static final String PRIVATE_KEY = "RSAPrivateKey";
    
    /**
     * RSA最大加密明文大小
     */
    private static final int MAX_ENCRYPT_BLOCK = 117;
    
    /**
     * RSA最大解密密文大小
     */
    private static final int MAX_DECRYPT_BLOCK = 128;
    
    /**
     * 私钥
     */
    private static final String privateKey = "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";
    
    /**
     * 公钥
     */
    private static final String publicKey = "MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQCcB2j59XCM4LstddJFqDMb/z6szuSeBPwmNBq+ytkQUyhA6wYpW/BvyAOeHIRDm2DXRCd+tDGeQAl8h+J6ILbqXIDNofbM/Jk4bWx0YBpPQ0uhOofAa+7aSdj3AHzDY1MabM1956Vs6VTMGkLV3XYN8dFPPXVJkmpNldHSIA4MdQIDAQAB";
    
    private static KeyFactory keyFactory = null;
    
    static {
        try {
            keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        } catch (NoSuchAlgorithmException e) {
            e.printStackTrace();
        }
    }
    
    
    
    /**
     * 获取base64加密后的字符串的原始私钥
     * @param keyStr
     * @return
     * @throws Exception 
     */
    public  static Key getPrivateKeyFromBase64KeyEncodeStr(String keyStr) throws Exception {
        byte[] keyBytes = Base64Utils.decodeString(keyStr);
        // 取得私钥
        PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);
        Key privateKey=null;
        try {
            privateKey = keyFactory.generatePrivate(pkcs8KeySpec);
        } catch (InvalidKeySpecException e) {
            e.printStackTrace();
        }
        return privateKey;
    }

    /**
     * 获取base64加密后的字符串的原始公钥
     * @param keyStr
     * @return
     * @throws Exception 
     */
    public static Key getPublicKeyFromBase64KeyEncodeStr(String keyStr) throws Exception {
        byte[] keyBytes = Base64Utils.decodeString(keyStr);
        X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(keyBytes);
        Key publicKey = null;
        try {
            publicKey = keyFactory.generatePublic(x509KeySpec);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return publicKey;
    }
    
    /**
     * <p>
     * 生成密钥对(公钥和私钥)
     * </p>
     * 
     * @return
     * @throws Exception
     */
    public static Map<String, Object> genKeyPair() throws Exception {
        KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance(KEY_ALGORITHM);
        keyPairGen.initialize(1024);
        KeyPair keyPair = keyPairGen.generateKeyPair();
        RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();
        RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();
        Map<String, Object> keyMap = new HashMap<String, Object>(2);
        keyMap.put(PUBLIC_KEY, publicKey);
        keyMap.put(PRIVATE_KEY, privateKey);
        return keyMap;
    }
    
    /**
     * 用私钥对信息生成数字签名
     * 
     * @param data
     * @return
     * @throws Exception
     */
    public static String sign(byte[] data) throws Exception {
    	return sign(data, privateKey);
    }
    
    /**
     * 校验数字签名
     * 
     * @param data
     * @param sign
     * @return
     * @throws Exception
     */
    public static boolean verify(byte[] data, String sign)
            throws Exception {
    	return verify(data, publicKey, sign);
    }
    
    /**
     * 公钥加密
     * 
     * @param data
     * @return
     * @throws Exception
     */
    public static byte[] encryptByPublicKey(byte[] data)
            throws Exception {
    	return encryptByPublicKey(data, publicKey);
    }
    
    /**
     * 私钥解密
     * 
     * @param encryptedData
     * @return
     * @throws Exception
     */
    public static byte[] decryptByPrivateKey(byte[] encryptedData)
            throws Exception {
    	return decryptByPrivateKey(encryptedData, privateKey);
    }
    
    /**
     * 私钥加密
     * 
     * @param data
     * @return
     * @throws Exception
     */
    public static byte[] encryptByPrivateKey(byte[] data)
            throws Exception {
    	return encryptByPrivateKey(data, privateKey);
    }
    
    /**
     * 公钥解密
     * 
     * @param encryptedData
     * @return
     * @throws Exception
     */
    public static byte[] decryptByPublicKey(byte[] encryptedData)
            throws Exception {
    	return decryptByPublicKey(encryptedData, publicKey);
    }
    
    /**
     * <p>
     * 用私钥对信息生成数字签名
     * </p>
     * 
     * @param data 已加密数据
     * @param privateKey 私钥(BASE64编码)
     * 
     * @return
     * @throws Exception
     */
    private static String sign(byte[] data, String privateKey) throws Exception {
    	byte[] keyBytes = Base64Utils.decodeString(privateKey);
        PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        PrivateKey privateK = keyFactory.generatePrivate(pkcs8KeySpec);
        Signature signature = Signature.getInstance(SIGNATURE_ALGORITHM);
        signature.initSign(privateK);
        signature.update(data);
        
        return Base64Utils.encodeByte(signature.sign());
    }
    
    /**
     * <p>
     * 校验数字签名
     * </p>
     * 
     * @param data 已加密数据
     * @param publicKey 公钥(BASE64编码)
     * @param sign 数字签名
     * 
     * @return
     * @throws Exception
     * 
     */
    private static boolean verify(byte[] data, String publicKey, String sign)
            throws Exception {
        byte[] keyBytes = Base64Utils.decodeString(publicKey);
        X509EncodedKeySpec keySpec = new X509EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        PublicKey publicK = keyFactory.generatePublic(keySpec);
        Signature signature = Signature.getInstance(SIGNATURE_ALGORITHM);
        signature.initVerify(publicK);
        signature.update(data);
        
        return signature.verify(Base64Utils.decodeString(sign));
    }
    
    /**
     * <p>
     * 公钥加密
     * </p>
     * 
     * @param data 源数据
     * @param publicKey 公钥(BASE64编码)
     * @return	BASE64编码
     * @throws Exception
     */
    private static byte[] encryptByPublicKey(byte[] data, String publicKey)
            throws Exception {
        byte[] keyBytes = Base64Utils.decodeString(publicKey);
        X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        Key publicK = keyFactory.generatePublic(x509KeySpec);
        
        // 对数据加密
        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
        cipher.init(Cipher.ENCRYPT_MODE, publicK);
        int inputLen = data.length;
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        int offSet = 0;
        byte[] cache;
        int i = 0;
        
        // 对数据分段加密
        while (inputLen - offSet > 0) {
            if (inputLen - offSet > MAX_ENCRYPT_BLOCK) {
                cache = cipher.doFinal(data, offSet, MAX_ENCRYPT_BLOCK);
            } else {
                cache = cipher.doFinal(data, offSet, inputLen - offSet);
            }
            out.write(cache, 0, cache.length);
            i++;
            offSet = i * MAX_ENCRYPT_BLOCK;
        }
        byte[] encryptedData = out.toByteArray();
        out.close();
       
        return Base64Utils.encode(encryptedData);
    }
    
    /**
     * <P>
     * 私钥解密
     * </p>
     * 
     * @param encryptedData 已加密数据(BASE64编码)
     * @param privateKey 私钥(BASE64编码)
     * @return
     * @throws Exception
     */
    private static byte[] decryptByPrivateKey(byte[] encryptedData, String privateKey)
            throws Exception {
    	encryptedData = Base64Utils.decode(encryptedData);
    	
        byte[] keyBytes = Base64Utils.decodeString(privateKey);
        PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        Key privateK = keyFactory.generatePrivate(pkcs8KeySpec);
        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
        cipher.init(Cipher.DECRYPT_MODE, privateK);
        int inputLen = encryptedData.length;
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        int offSet = 0;
        byte[] cache;
        int i = 0;
        // 对数据分段解密
        while (inputLen - offSet > 0) {
            if (inputLen - offSet > MAX_DECRYPT_BLOCK) {
                cache = cipher.doFinal(encryptedData, offSet, MAX_DECRYPT_BLOCK);
            } else {
                cache = cipher.doFinal(encryptedData, offSet, inputLen - offSet);
            }
            out.write(cache, 0, cache.length);
            i++;
            offSet = i * MAX_DECRYPT_BLOCK;
        }
        byte[] decryptedData = out.toByteArray();
        out.close();
        return decryptedData;
    }
    
    /**
     * <p>
     * 私钥加密
     * </p>
     * 
     * @param data 源数据
     * @param privateKey 私钥(BASE64编码)
     * @return
     * @throws Exception
     */
    private static byte[] encryptByPrivateKey(byte[] data, String privateKey)
            throws Exception {
        byte[] keyBytes = Base64Utils.decodeString(privateKey);
        PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        Key privateK = keyFactory.generatePrivate(pkcs8KeySpec);
        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
        cipher.init(Cipher.ENCRYPT_MODE, privateK);
        int inputLen = data.length;
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        int offSet = 0;
        byte[] cache;
        int i = 0;
        // 对数据分段加密
        while (inputLen - offSet > 0) {
            if (inputLen - offSet > MAX_ENCRYPT_BLOCK) {
                cache = cipher.doFinal(data, offSet, MAX_ENCRYPT_BLOCK);
            } else {
                cache = cipher.doFinal(data, offSet, inputLen - offSet);
            }
            out.write(cache, 0, cache.length);
            i++;
            offSet = i * MAX_ENCRYPT_BLOCK;
        }
        byte[] encryptedData = out.toByteArray();
        out.close();
        return encryptedData;
    }
	
    /**
     * <p>
     * 公钥解密
     * </p>
     * 
     * @param encryptedData 已加密数据
     * @param publicKey 公钥(BASE64编码)
     * @return
     * @throws Exception
     */
    private static byte[] decryptByPublicKey(byte[] encryptedData, String publicKey)
            throws Exception {
        byte[] keyBytes = Base64Utils.decodeString(publicKey);
        X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        Key publicK = keyFactory.generatePublic(x509KeySpec);
        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
        cipher.init(Cipher.DECRYPT_MODE, publicK);
        int inputLen = encryptedData.length;
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        int offSet = 0;
        byte[] cache;
        int i = 0;
        // 对数据分段解密
        while (inputLen - offSet > 0) {
            if (inputLen - offSet > MAX_DECRYPT_BLOCK) {
                cache = cipher.doFinal(encryptedData, offSet, MAX_DECRYPT_BLOCK);
            } else {
                cache = cipher.doFinal(encryptedData, offSet, inputLen - offSet);
            }
            out.write(cache, 0, cache.length);
            i++;
            offSet = i * MAX_DECRYPT_BLOCK;
        }
        byte[] decryptedData = out.toByteArray();
        out.close();
        return decryptedData;
    }
    
    /**
     * <p>
     * 获取私钥
     * </p>
     * 
     * @param keyMap 密钥对
     * @return
     * @throws Exception
     */
    public static String getPrivateKey(Map<String, Object> keyMap)
            throws Exception {
        Key key = (Key) keyMap.get(PRIVATE_KEY);
        return Base64Utils.encodeByte(key.getEncoded());
    }

    /**
     * <p>
     * 获取公钥
     * </p>
     * 
     * @param keyMap 密钥对
     * @return
     * @throws Exception
     */
    public static String getPublicKey(Map<String, Object> keyMap)
            throws Exception {
        Key key = (Key) keyMap.get(PUBLIC_KEY);
        
        return Base64Utils.encodeByte(key.getEncoded());
    }
    
}
